const headers = { 'Content-Type': 'text/javascript' };
const c = new Caseless(headers);
c.set('content-type', 'text/css');
expect(headers).to.eql({ 'Content-Type': 'text/css' });
expect(c.getKey('content-type')).to.equal('Content-Type');
expect(c.get('content-type')).to.equal('text/css');
expect(c.has('content-type')).to.be.true;
c.remove('content-type');
expect(c.has('content-type')).to.be.false;
